Closes mailbox and unlocks it.
The Unlock Method syntax has these parts:
||An expression evaluating to an object
of type wodMailbox.
This method releases mailbox file so you can externally
add new messages to it, change it by some other programs or
delete it. After this method is called you can specify new
property to point to different mailbox file.
After calling this method all the messages held by
wodMailbox are discarded from memory, and you cannot access